Tuesday, April 24, 2012

scintillating scotoma

a few minutes ago (~22:35), reading, and i notice that letters are hard to see. that sensation of having a bright afterimage at fixation; it's moving rightward, usually it's been leftward (I haven't taken notes on the past 2 occurrences, sadly..); this it is at least the first of the last 4 to go through the right field, if not longer.

it begins with just a weird sense of scotoma-ness, very near fixation, but the blind areas are hard to pin down - they seem to change very rapidly, or else it's more a sensation of blindness rather than actual blindness. it's strange how it sticks at fixation even as it arcs out into the periphery; it seems it always arcs into the lower field, after arcing just a bit above fixation. i've not noticed yet one passing across the field, maybe it is restricted to hemisphere?

it's almost gone at this point (almost 30 minutes after the first signs), and all that's left is a flickering at the very top of my visual field, as if there's a light flashing on my eyebrows; interestingly, if i look up, it disappears, which is strange because it should be attached to the field location. i can look up, it disappears, look down again and it reappears. maybe was an interaction with the reflection of room/computer lights off my eyeglass frames? can't test, it's all gone now..

and i have a headache (actually it started a few minutes in; the light show was so slow to start, i thought we were skipping straight to the headache for a few minutes, a bit of disappointment, but it worked out!)

also, some hints: today and yesterday, i several times wondered if i wasn't going to get a headache soon, without understanding why. not sure what sets off those feelings.. this afternoon, i thought i saw some flashes at some point when i was walking down the hallway, and that really made me suspicious; and, all day, really tight, painful muscle spasm throughout my upper back, both sides trapezius.

23:05

map below: i have a few of these now, should get to processing them this summer..



Edit: look at what this guy has done: http://www.pvanvalkenburgh.com/MigraineAura/MigraineAuraMaps.html. pretty amazing.

also, i did wind up writing a script to analyze these plots; once I get some stuff settled, i'll post those in a new entry.

Friday, April 20, 2012

lazy friday dark adapt


Spent afternoon of Friday, 4-20-12, with a ~3 log unit (~.2%) ND filter over my right eye. Made the following observations:
(Took the filter off after about 4 hours. It wasn’t bothering me much anymore, but I think the plastic and rubber stuff in the goggles was irritating my eyes, which were starting to feel kind of dry and red. Light adaptation is really fast, it’s just been a minute and the (formerly dark adapted) right eye’s image only seems slightly brighter than the left’s.)
  1. Noise: the dark adapted eye’s view is noisy, and the noise intrudes into the dominant view. It’s irritating. The dark adapted view isn’t being suppressed, though, it’s there like a ghost. Double images, from depth, are strikingly noticeable, not sure why.
  2. Pulfrich effect: first time I’ve really seen this work. I put my index fingers tip-to-tip and move one from side to side, fixating on the still one, and the moving finger looks like it’s rotating. My hand even feels like it’s rotating.
  3. Pulfrich effect 2: Fusion isn’t always working, but I seem to be ortho a lot of the time. I just noticed, though, that if I make quick motions, e.g. a flick of a finger, there’s a delay in the motion between the two eyes; the dark adapted image is delayed by several hundred milliseconds! Especially obvious if I focus at distance so I have a double image of the finger. Explains the strong Pulfrich effect.
  4. Noise 2: Just looked at some high frequency gratings. With the dark-adapted eye, the noise was very interesting, looked like waves moving along the grating orientation, i.e. along the bright and dark bars there’s a sort of undulating, grainy fluctuation.
  5. I still have foveal vision and color vision, but both are very weak. Dim foveal details are invisible. High contrast details (text, the high frequency gratings) are low contrast, smudgy..
  6. Motion is kind of irritating, I think because it brings about lots of uncomfortable Pulfrich-type effects. Even eye movements over a page of text can be bothersome, because there is always an accompanying, delayed motion. I’m guessing that the saccade cancellation is being dominated by the light-adapted eye, and so I’m seeing the dark-adapted saccades. I don’t notice a depth effect, but walking around in the hallways I do feel kind of unsteady, maybe because of motion interfering with stereopsis. If objects are still, stereopsis seems to be okay.
  7. If I take vertical and horizontal gratings (64c/512px), add them together, then look at them at 25% contrast from about 30cm (here at my desk), I don’t see a compound grating – I see patches of vertical and patches of horizontal. I’ve never noticed this before; I wonder what differences there are with scotopic vision and cross-orientation suppression..
  8. I tried to watch my light-adapted eye move in a mirror, but the dark-adapted eye just couldn't see well enough. I think a weaker filter would make it possible.

Thursday, April 19, 2012

Memes and Pharmacies

That rivalry proposal went in last Monday with no problems, along with a long-festering manuscript, so it seems I took a week off from writing. Now I have progress reports to do, presentations to prepare, other manuscripts to complete, on and on.. I need to make sure I keep up with this journal, which seems to be helping in keeping my writing pace up.

Vacation is over!

About 12 years ago, I read the Meme Machine by Susan Blackmore. It was around the time that I decided to major in psychology, and I was reading all this Dan Dennett Douglas Hofstadter stuff, but it was her popular science book that really had a big effect on me - I would say that it changed my worldview completely, to the extent that I would identify myself as a memeticist when discussions of religion or that sort of thing came up (it was still college, see) - I really felt like it was a great idea, that human culture and human psychology could be explained as essentially a type of evolutionary biology. I still believe it, and so I suppose this book still really sits near the base of my philosophical side, even though I don't think about these things so much anymore.

I bring this up because the other night Jingping and I were talking about being tricked, since this was the topic of a Chinese textbook lesson I had just read, and I recounted the story of being completely conned by a thief once when I was a clerk working at CVS. I wound up going on more generally about working there, and I remembered that I had worked out a memetics-inspired 'model' of that store, which I hadn't thought about in a long time. One of the things about the memetics idea that had really gotten to me was that you could see social organizations as living creatures with their own biological processes - not that this is an idea original to Blackmore, and I'm sure that's not the first place I had heard it (like I said, I was also reading Dennett and Hofstadter at the time), but she did work it into a larger sort of scientistic system which seemed to simplify and unify a lot of questions.

Now I realize that the criticisms of memetics that I heard from professors in college (when I questioned them about it) were mostly right, in that it mostly consists of making analogies between systems; only in the last few years, with the whole online social networking advent, has a real science of something like memetics actually gotten off the ground (this is a neat example from a few weeks ago), and it's very different from what had been imagined when the idea was first getting around.

Anyways, I thought I'd detail here my biology-inspired model of a CVS store, ca. 2001. I have a notebook somewhere where I had detailed a whole system, with functional syntax and everything, for describing social organizations in terms of cellular, metabolic systems. This might have been the first time that I had tried to put together a comprehensive model of a system, now that I think of it. The store, I thought, was itself a cell in a larger CVS system dispersed across the city, which itself was a system dispersed across the country. I was mainly interested in the store level, where you could see different components acting as reagents. It was a strongly analogical system, but not completely analogical, to plant metabolism: a plants needs carbon, so it uses sunlight to break down carbon dioxide, releasing the unneeded oxygen back into the world. A store needs money, so it uses salable products to break down a money-human bond, releasing the human back into the world.

Of course, with plants the sunlight comes free from heaven - all the plant can do is spread out and try to catch it - while salable products must be delivered from another part of the CVS system: the distribution center. The distribution center emits reagents to the stores, where the money-human bond is broken down. The CVS system also emits catalytic agents into the world - advertisements - to facilitate the crucial reaction. The money absorbed by the system is energy which is used to drive the system through a reaction not unlike oxidation - the money-human bond is reformed systematically, with employees as the human component. This reformation is what really drives the system. Those new human-money bonds then go out into the world and fulfill the same function, breaking apart, as they interact with other businesses.

Looking at a business in this way totally changed the way I understood the world. Businesses, churches, governments, political parties, armies - all of them can be thought of as living creatures, or as organs of larger creatures, rather than as some sort of human means-to-an-end. By changing perspective between levels, we can see ourselves as means to the ends of these larger systems, just as our cells and organs are means to ours. Now I'm finally getting around to reading straight through Hofstadter's GEB, and so I can see that this general idea of shifting perspective across levels is an old one that has been astonishing people for a long time. But for me, coming to see human culture as as being alive was a fundamental shift in my intellectual development, one that hasn't really been superseded since. I haven't become a real memeticist yet, but it's all still there, underneath... these tiny tendrils of memetics live yet...

Tuesday, April 03, 2012

dream post!

recurring dream:

jingping and i are trying to get to the train station. the city is like a cross between boston and chicago - it's boston but with lots of overhead walkways and more of that chicagoesque feeling of sharp-edged criss-crossedness.

lots of things happen as we're on our way, it's like we're being chased, but the recurring part is where we get into the station and have to start climbing a stairwell, up and up. i know what's going to happen as the dream progresses. there's a fear of falling down the stairwell, but what happens is that it gets narrower and narrower, less and less place to put your feet, and you're crawling finally up a spiral tunnel, until you can't go further because there's just not enough space - around this point i know it's a dream, because i'm thinking that it can't really be this way, and i'm trying to change it because it's so damn uncomfortable. even in the dream, i'm thinking, why does this happen, why can't i fix it?

once it got to that point, i realized that my eyes were closed, but i couldn't open them, and yet i could still kind of see the twisting stairwell tunnel ahead - and there was a confusing sensation of being able to see but not being able to see, at the same time (interesting relevance to the visual consciousness stuff i was wondering about earlier, which is really why i'm writing it down). i was feeling around for the gap ahead, to see if i would fit, and i knew jingping was behind me and i couldn't back up, but i also felt like i could see it all...

i think i woke up soon after. i figure that noticing my eyes were closed and not being able to open them, and yet still having a sense of vision, must have been REM atonia - sleep paralysis, the sort of thing that gives you the feeling of being trapped and immobile in a bad dream.

anyways, i'm pretty sure i've had this dream a few times, the "shrinking stairwell dream".

dream post, yeah!

Monday, April 02, 2012

model update

I'm working on other things lately, but I did finally get that multi-channel rivalry model working - main problem was that I had written the convolution equations out wrong. I had to do the convolution there in the code because the filter array is irregular - there's no function to call for 2d irregular-array convolution, much less for switching the convolution between different layers.

Here's what I had done:

Z´(x) = Z´(x) + F(x)·Z(x), where x is a vector of spatial indices, Z is the differential equation describing the change in excitation or adaptation over time, F is basically just a 2-d Gaussian representing spatial spread of activation for the inhibitory or excitatory unit, and Z´ is (supposed to be) the differential convolved with the spread function.

Now that doesn't make any sense at all. I don't know what that is. In the actual code that equation was actually 3 lines long, with lots and lots of indices going on because the system has something like five dimensions to it; so, I couldn't see what nonsense it was.

This is how it is now:

Z´(x) = Z´(x) + sum(F(x)·Z(x))*F(x)

THAT is convolution. I discovered what was going on by looking at the filter values as images rather than as time plots; Z and Z´ didn't look different at all! Z´ should look like a blurred version of Z. Such a waste of time...

Anyways, it kind of works now. Different problems. Not working on it until later in April. The 'simple' single resolution model was used to generate some images for my NRSA application. Here's a sample simulation of strabismus (with eye movements):

video